Process for crimping filaments and yarns

ABSTRACT

The invention provides a process for crimping filaments and yarns wherein a plurality of filamentary yarns is drawn by fluid media into an injector nozzle, piled up and stuffed in a blowing chamber. The individual yarns are fed through separate channels in the injector nozzle and kept separate by currents of fluid media while being laid and stuffed in a common blowing stuffing chamber. A plurality of filamentary yarns can be crimped simultaneously in one stuffing chamber and then wound up separately. The texturized yarns obtained are characterized by a fine crimp, high crimping contraction and high elastic pull.

United States Patent [191 Strutz et al.

[ PROCESS FOR CRIMPING FILAMENTS AND YARNS [75] Inventors: Hans-Jiirgen Strutz; Ingolf Jacob,

both of Bobingen; Johann Seelig, Schwabmunchen, all of Germany [73] Assignee: Hoechst Aktiengesellschaft,

Frankfurt am Main, Germany [22] Filed: Apr. 5, 1973 [21] Appl. No.: 348,226

[30] Foreign Application Priority Data [451 July 22,1975

3,378,900 4/1968 Spicer 28/72.]4 3,409,956 11/1968 Longbottom et al. 28/721 1 X 3,543,984 12/1970 Mansfield 28/7214 UX 3,703,754 11/1972 Blanc et al 28/7214 3,827,] 13 8/1974 Vidal et al. 28/7214 FOREIGN PATENTS OR APPLICATIONS 1,951,468 10/1970 Germany 28/7214 1,043,647 9/1966 United Kingdom 226/97 Primary Examiner-Robert R. Mackey Attorney, Agent, or Firm-Connolly and Hutz -[57] ABSTRACT The invention provides a process for crimping filaments and yarns wherein a plurality of filamentary yarns is drawn by fluid media into an injector nozzle, piled up and stuffed in a blowing chamber. The individual yarns are fed through separate channels in the injector nozzle and kept separate by currents of fluid media while being laid and stuffed in a common blowing stuffing chamber. A plurality of filamentary yarns can be crimped simultaneously in one stuffing chamber and then wound up separately. The texturized yarns obtained are characterized by a fine crimp, high crimping contraction and high elastic pull.

5 Claims, 7 Drawing Figures PROCESS FOR CRIMPING FILAMENTS AND YARNS The present invention relates to a process for crimping filaments and yarns wherein a plurality of filamentary yarns are drawn by the current of a motive fluid into an injector nozzle, piled up in a blowing chamber and stuffed.

The development of texturizing processes, i.e., processes for the manufacture of bulked yarns, is a result of the desire to confer upon smooth endless filaments, for example synthetic filament yarns, the bulk of fiber yarns of natural fibers, such as cotton or wool. For yarns of fine denier the false twist texturizing processes have become the most important industrial processes, while for coarse denier stuffing chamber processes, for example the jet stufferbox texturizing process, have gained in importance. In part, stuffer box processes are used only to achieve a more dense packing of the yarns for certain treatment stages, for example dyeing, fixing and the like.

In the jet stufferbox texturizing process the filamentary yarn is blown irregularly by an injector nozzle into a mostly cylindrical blowing chamber where it is laid on already conveyed filamentary material. The motive fluid then escapes by lateral openings in the front section of the blowing chamber (see patent of the German Democratic Republic No. 17,786, filed Oct. 27, 1957, published Aug. 25, 1960). The filament is crimped by the folding when it is laid and the crimp is set by a heat treatment, for example by heating the blowing chamber. The bulked and compressed rope-like yarn package obtained after the laying process is continuously removed from the blowing chamber. This can be done, for example, as described in Federal Republic of Germany, German Offenlegungsschrift No. 2,036,856 published Feb. 4, 1971, by overpressure prevailing in the chamber as a result of an incomplete release of a gaseous motive fluid. The wall friction occuring with the motion of the texturized yarn package must be overcome by the expelling force. The yarn can be brought again from the stuffed state into a stretched state and wound up on bobbins.

To increase the capacity of a jet stufferbox texturizing device attempts are being made simultaneously to introduce through the nozzle as many filamentary yarns as possible, mutually to texturize them, but to wind them up separately. When several filamentary yarns are commonly laid in the blowing chamber they mix and become entangled. In the subsequent separation, pulled out filament loops are forcibly formed or the filaments are even damaged mechanically, for example, broken.

The fineness of texturizing, defined as the number of crimps unit length is decisively influenced also by the cross section of the blowing chamber. The smaller the cross section the more intense and uniform the texturization. On the other hand, with a small cross section of the blowing chamber, only a small number of filamentary yarns can be texturized simultaneously. Moreover, with a reduction of the cross section of the blowing chamber, the influence of the wall friction strongly increases, whereby the running safety of the process is impaired.

To overcome the aforesaid disadvantages several filamentary yarns should be commonly treated in one blowing chamber texturizing device, but in the entire device they should be maintained separated in such a manner that they do not interfere with each other when being drawn in and laid. By a separate laying of the yarns a reduced cross section of the stuffing space would result for each filament.

It has been found that rigid mechanical separating means in a blowing chamber texturizing device do not ensure a satisfactory separation of the yarns.

The separating effect of the yarn package into individual filamentary yarns can be improved with regard to known processes by passing the yarns through separate channels in the injector nozzle, but the result is not yet satisfactory.

It has also been proposed to keep the filaments separate by guide plates until they are laid. By subdividing the blowing chamber cross section in individual zones in each of which one filamentary yarn is laid, the stuffing space available for each filament has an effective cross section which is much smaller than the total blowing chamber cross section. This would improve texturization. This principle has, however, the following drawback: the guide plates require space which does not exist with the desired small dimensions of the blowing chamber and by the motive fluid the incoming filaments are pressed against the guide plates where they are subjected to an additional friction. At the end of the guide plates interspaces having the thickness of the guide plates remain between the crimped yarn packages which cause them to bend whereby the continuous transport of the yarn packages in the blowing chamber may be disturbed.

While rigid machanical separating means are not capable of improving the known jet stufferbox texturizing process, it has been found that the filamentary yarns can be kept separate by currents of a fluid medium.

The present invention provides a process for crimping filaments and yarns wherein a plurality of filamentary yarns are drawn by the current of a motive fluid into an injector nozzle, piled up in a blowing chamber and stuffed, which comprises introducing the individual filamentary yarns through separate channels into the blowing chamber, laying them and stuffing while being kept separate by the current of a fluid medium.

Especially good results are obtained by keeping separate the individual filamentary yarns by partial currents of the motive fluid and/or by currents of a fluid medium different from the motive fluid.

The crimp produced by the process of the invention may be permanent or it may only serve to achieve a dense packing of the yarns for certain processing stages. Processes are preferred in which the motive fluid and/or the separating medium produce a permanent crimp of the filaments. When a dense packing of the yarns is desired, the motive fluid and separating medium should not produce a permanent crimp.

The present invention may be performed in a device for carrying out the process of the invention in which the injector nozzle has several separate channels for filament feeding and one or several channels for the separating gas which are arranged between filament feed channels.

A device is preferred in which the filament feed channels are disposed symmetrically around a central separating gas channel.

The device will now be described with reference to the accompanying drawings given by way of example, wherein FIGS. 1 to 7 represent preferred embodiments FIGS. 4 to 7 are cross sectional views of examples of' injector nozzles according to the invention along line IIII of FIG. 1.

Referring to the drawings:

The motive fluid streams through inlet 1 into distributing zone 2 of the injector nozzle and escapes at a high speed through annular gap 3. Annular gap 3 is formed by the conical nozzle pin 4 and counter cone 5, its cross section being determined by the position of nozzle pin 4 which is adjusted by spacer rings 6 or by other suitable means.

The filamentary yarns fed through channels 7 are taken up by the motive fluid streaming through the annular gap 3, transported into the blowing chamber 8 where they are piled up. I

In FIG. 2, nozzle pin 4 is provided with a central boring 10 which ends in the tip of the pin in the form of a star-shaped channel 9 through which the fluid medium for separating the filamentary yarns is supplied.

It can be clearly seen in FIG. 2 that the arrangement of the feed channels 7 for the yarns and the star-shaped channel 9 for the separating gas ensures a separation of the yarns one from the other.

The current of the separating medium creates a kind of hollow duct between two adjacent yarns so that the individual filamentary yarns are laid in one third only of the cylindrical blowing chamber. The separating medium acts like a concomitantly moving wall, hence it reduces the effective cross section of the stuffing space without increasing the friction on the wall.

FIGS. 4 through 7 are cross sectional views on line IIlI of injector nozzles similar to that of FIG. 2. The injector nozzle shown in FIG. 6 has a pyramidal nozzle pin instead of an axially symmetrical nozzle pin 4. In this case the feed channels 7 for the filamentary yarn and the channels for the separating gas 9 alternate in rectilinear direction one beside the other.

It has surprisingly been found that the very simple construction of the injector nozzle as shown in FIG. gives good results. The four yarn feed channels 7 are arranged symmetrically around the circular channel for the separating gas. The divergence of the current of separating medium is obviously sufficient to keep separate the four filamentary yarns.

The separating medium is supplied through conduit 11 and passes into boring through a lateral conduit 12. When in the process of the invention the separating medium and the motive fluid are the same, conduit 12 may end in distributing zone 2 and the connection 11 can be dispensed with.

In the process of the invention the current of separating medium obviously creates hollow ducts between the yarns so that the filaments do not intermingle while being laid and are mush easier to separate after laying.

Each of the incoming filamentary yarns is laid individually. The effective cross section of the stuffing space, i.e., the portion of the cross sectional area of the blowing chamber at the disposal of each yarn depends on the number of simultaneously texturized yarns. The reduction of the cross sectional area of the stuffing space for each yarn improves the intensity of texturization and the uniformity.

When a separating medium having a high outlet speed is used in the process of the invention, the separating medium may simultaneously act as additional motive fluid. The filamentary yarns are then caught all around by the fluid whereby the draw-in tension increases and temporary variations thereof diminish.

The number. shape, and the arrangement of the yarn channels and the gas channels in the injector nozzles according to the invention must be adapted to the requirements in each case. The nozzle may be provided with two, three, four, or more yarn channels, the upper limit depending onthe cross section of the blowing chamber. The channels may have a round, elliptic, or quadratic cross section, or a cross section of another geometric shape. They can be arranged in various ways.

As shown in FIGS. 1 to 7, the inlet and outlet openings of the yarn channels can be arranged on circles or longitudinally one beside the other. Other arrangements, for example on ellipses, regular or irregular polygons, are also possible. In order that the separating medium issues as near to the filamentary yarns as possible, the shape and the arrangement of the gas channel are chosen in conformity with the arrangement of the yarn channels. Instead of round borings there may also be chosen borings having star-shaped or elliptic cross sections. A'gas channel should always be arranged in such a manner that two filamentary yarns from adjacent channels are separated by the separating medium issuing from the gas channel. The nozzle pin 4 may have the shape not only of a circular cone but also of an elliptic cone, or possibly theshape-of a pyramid or a wedge. Especiallygood results are obtained with a biconical nozzle pin having a central round boring as the channel for the separating gas and around which four yarn channels are arranged in such a manner that the inlet and outlet openings thereof are on concentric circles symmetric with respect to the cone axis.

A biconical nozzle pin, i.e., a conical nozzle pin with which the opening angle of the cone suddenly changes at one place, yields a particularly uniform flow of the motive fluid through the annular gap 3.

The process of the invention can be used for all yarns of natural fiber-forming materials, such as wool, synthetic fibers, such as rayon fibers, cellulose acetate fibers; and synthetic yarns and filament yarns, for example of polyesters or polyamides, or mixtures of the aforesaid materials. The total denier and individual denier of the filaments can vary within wide limits, as well as the number of yarn twists per unit length.

The selection of the motive fluid essentially depends on the subsequent processing. To produce permanently texturized yarns of thermoplastic materials, a plasticizing medium having elevated temperature will be used, for'ex'ample steam, possibly with the addition of a plasticizer. When a temporary stuffing without permanent deformation of the filaments is desired, an inert medium, such as compressedair, will be used The selection of the medium used for keeping separate the filamentary yarns likewise depends on the desired properties of the final yarn. Thus steam may be chosen as motive fluid and as' s'eparating medium, a lubricating agent may be blown in with compressed air in the form of a mist. A simultaneous dyeing is likewise possible.

The dimensions of the blowing chamber are adapted to the special requirements. Its length decisively determines the residence time of the filaments and hence, the setting of the crimp. As in the known processes, a circular cross sectional area is mostly chosen.

In the known jet stufferbox texturizing processes, blowing chambers of small cross section are used in order to obtain a fine crimp. On the other hand, a reduction of the blowing chamber cross section involves an insufficient spreading apart of the individual filaments of the filamentary yarn when entering the blowing chamber. A complete spreading apart of the individual filaments of the yarn at this point is, however, a necessary prerequisite for a uniform crimp. Moreover, a reduction of the cross section of the blowing chamber increases the wall friction.

As compared therewith, in the process of the invention, the effective cross section of the stuffing space for each filamentary yarn, i.e., the cross section of each package of crimped individual yarn, approximately corresponds to the cross section of the blowing chamber divided by the number of filamentary yarns.

To carry out the process of the invention, the blowing chamber need not have a cylindrical shape, different shapes may also be chosen (Patent of the German Democratic Republic No. 20, 597 filed Mar. 8, 1957, published Jan. 10, 1961).

A further advantage of the process of the invention is the high constant feed tension of the filamentary yarns which allows of a uniform operation.

The separation of the filamentary yarns according to the process of the invention substantially prevents the individual filaments from entangling so that yarns are obtained having an unobjectionable quality without filament damage, i.e., without broken filaments or loops and slubs.

It is possible simultaneously to texturize several filamentary yarns in a safe manner whereby the capacity of the jet stufferbox texturizing process is considerably improved. The number of filamentary yarns is chosen in each case according to economical considerations:

On the one hand, the economy increases, of course, with the number of filamentary yarns, while on the other hand, troubles with one filamentary yarn necessitate interruption of the process for all filamentary yarns, that is to say, the consequences of a trouble increase with increasing number of filamentary yarns. These are the reasons why no more than 8 filamentary yarns will mostly be texturized simultaneously.

The yarn texturized according to the invention are used in many textile fields of application. An especially important field is the manufacture of carpets, mainly tufted carpets.

The bulk of the yarn, defined by the crimping characteristics, i.e., number of crimps per unit length, crimping contraction and elastic pull, substantially determines the handle and the hard-wearing properties of a carpet. Owing to their uniformity and the fact that they are easy to separate after jet stufferbox texturizing, the yarns produced by the process of the invention yield carpets with uniform, well defined knobs, that is to say carpets of high quality with a clear and smooth appearance.

In the process of the invention the effective cross section of the stuffing space can be strongly reduced. It is L L, L,

and EP= I00 '1' in which L is the length of a l m long yarn loop under a load of 0.2 g/dtex which had previously been heated at 60 65C without tension for 10 minutes in distilled water with the addition of l g per liter of the sodium salt of diisobutylnaphthalene sulfonic acid and then loaded with the aforesaid load for 10 seconds in air.

The yarn loop is then dried for 1 hour at 60 65C without tension in circulating air and allowed to cool for a further hour under normal climatic conditions, i.e., 20C, 65 of relative humidity.

The length L is determined under a preliminary load of 0.002 g/dtex and the length L is determined under 0.02 g/dtex, in each case after the action of the load for 30 seconds.

The number of crimps per centimeter is determined with an individual filament having a length of about 50 mm under a load of 0.02 g/dtex by counting under a magnifying-glass all crimps to the right and left of an imaginary center line and dividing the number of crimps by the length of the individual filament under the aforesaid load. The individual filament was taken from a sample having undergone the same preliminary treatment, but without the load of 0.2 g/dtex.

To improve the statistical accuracy the tests were carried out with about 25 samples, the mean values were determined as well as the deviation of the crimping characteristics.

The above is directed to the production of double colored twist yarns or from yarns having different dyeing properties by twisting after texturizing. Only Melange yarns are obtainable by blow-texturizing processes known in the art.

The rope like bundle of filamentary yarns can be intermediately stored in suitable containers and separated again into the individual yarns, if desired after having been subjected to further processes, for example dyeing.

The following examples illustrate the invention.

EXAMPLE 1 The dependence of the crimping characteristics, i.e., crimps per centimeter (e/cm), crimping contraction (CC) and elastic pull (EP) on the effective cross section of the blowing chamber is demonstrated. In the known jet stufferbox texturizing process the effective cross section of the blowing chamber corresponds to the real blowing chamber cross section, whereas in the process of the invention it only corresponds to a fraction thereof.

A jet-stufferbox texturizing device as described in DOS 2,036,856 was operated with three different types of injector nozzles:

b. an injector nozzle B in accordance with the invention, the nozzle pin of which was provided with two channels for the filamentary yarns and a central channel for the separating gas (as shown in FIG. 5, however with two opposite instead of four channels for the filamentary yarns);

c. an injector nozzle C in accordance with the invention, the nozzle pin of which was provided with four channels for the yarn and a central boring for the gas (as shown in FIG.

The geometrical dimensions of all three injector nozzles were identical, the diameter of the issuing end of the nozzle pin being 3.4 mm, the length of the conical part of the nozzle pin 31 mm. The construction of the injector nozzles substantially corresponded to that of the nozzle shown in FIG. 1. They had, however, no connection 11 as saturated steam at a pressure p, was used as motive fluid and as separating gas. The boring 12 directly ended in distributing zone 2. In all three tests 245 g per minute of steam were passed through the respective nozzle. The cylindrical blowing chamber of the texturizing device had a length of 500 mm and an inner diameter of 8 mm. The front section of the blowing chamber, which was provided with outlet holes for the steam, was surrounded by a further chamber wherein the escaping steam was collected and maintained at a constant pressure 2 by means of a reducing valve. The material to be texturized was polyamide 6. In each test four filamentary yarns each having a denier of dtex 1100f67 were used.

With injector nozzle A all four yarns passed through the central channel; with injector nozzle B two yarns each were run through either of the two feed channels; while with injector nozzle C one filamentary yarn each was passed through the four feed channels. The feeding speed was 430 m/min. The crimping characteristics obtained are listed in the following table.

pressure p, P c/cm CC EP (atm. gauge) injector nozzle A 4.0 0.8 13 injector nozzle B 4.0 0.8 12 16 injector nozzle C 4.0 0.8 13 31 17 injector nozzle A 4.6 1.3 1 1 27 15 injector nozzle B 4.6 1.3 12 31 17 injector nozzle C 4.6 1.3 14 33 19 It can be seen that the crimping characteristics obtained with injector nozzles B and C of the invention are distinctly superior to those obtained with injector nozzle A.

EXAMPLE 2 b. an injector nozzle D, the nozzle pin of which was provided with four channels for the filamentary yarns and did not have an inlet for the separating gas (obtained by closing the gas channel of injector nozzle C) 'c. an injector nozzle C according to the invention (as in Example 1).

The injector nozzles had the same dimensions as in Example 1. Thedimensions of the blowing chamber were as follows: length 500mm, inner diameter 6 mm. Theexperiments were carried out with polyamide 6 filament yarns; in Experiment (a) two filamentary yarns each having a denier dtex 1 f 67 were passed through nozzle A and in Experiments (b) and (0) using nozzles D and C, four filamentary yarns each having a denier dtex l 100f67 were passed through. As separating gas and motive fluid saturated steam was used under operating pressures p 4.3 atmospheres gauge and p 1.3 atmospheres gauge. The throughput of the saturated steam was as follows: 210 g/min each through nozzlesA and D, 260 g/min through nozzle C, including the-steam portion used as separating gas. The resulting draw in forces were 14 15 g/filamentary yarn with nozzle A, 17 l8 g/filamentary yarn with nozzle D and-23 24 g/filamentary yarn with nozzle C.

The outlet speed of the package of filamentary yarns from the blowing chamber was adjusted in such a manner that in all three experiments the package had a weight of 4.5 g/m.

To measure the separability of the packages of filamentary yarns into the individual yarns the following method was used:

A rope-like yarn package which consisted of two filamentary yarns in Experiment (a) and of four filamentary yarns in Experiments (b) and (c) and which had a weight of 4.5 g/m ineach case, was vertically suspended and loaded with a weight of 100 gms. whereby its length increased by four to five times its original length. At the upper end of the package the yarns were separated and a measuring arm was introduced between them in such a manner that an equal number of filaments was on either side of the arm. As a measuring arm the measuring head of an electronic tensiometer R-1092 of Messrs. Rothschild, Zurich, Switzerland, was used. The measuring head carried a roll having a diameter of 10 mm to separate the two groups of filaments. The measuring arm was passed downward over a measuring distance of ---1 meter at a constant speed of 5 cm/sec. The force acting on the measuring arm in the direction opposite to the. moving direction was recorded;rit is a measurement for the entanglements between the two groups of filaments. Firm entanglements resulting in drawn out filament loops and/or filament breakings are perceived by distinct force peaks.

In several measurements the frequencies of entanglements which necessitated for separation a force above 100 g at the measuring arm was on the average:

Experiment (a) 20 entanglements per meter Experiment (b) 3 to 4 entanglements per meter Experiment (c) O to 1 entanglement per meter Hence, the packages of Experiments (b) and (0) were much less entangled than the package of Experiment (a). The experiment using the injector nozzle according to the invention gave the best result with the lowest number of entanglements, and thus the best yarns, from which carpets with very few broken filaments or loops can be produced. Moreover, the highest draw in tension of the filamentary yarns in Experiment ensures the safest running conditions.

EXAMPLE 3 The invention is not limited to polyamide filaments. in a jet stufferbox texturizing device with injector nozzle C according to the invention (as defined in Example 1) poly(butylene terephthalate) and poly (caprolactam) yarns were texturized. The cylindrical blowing chamber had a length of 500 mm and an inner diameter of mm. One poly (butylene terephthalate) filamentary yarn had a denier dtex 2000f 134. the individual filaments had a round profile. The denier of one poly (caprolactam) filamentary yarn was dtex 2200 f 134 with a trilobal profile of the individual filaments. Four filamentary yarns each were simultaneously texturized, the feed rate of the yarn being 400 m/min. Saturated steam was used as motive fluid and separating medium; the steam pressure p and 2 indicated in the following table were as in Example '1. The crimping characteristics obtained are indicated in the following table.

What is claimed is:

1. In a process for crimping filaments and yarns in which a plurality of filamentary yarns are drawn by the current of a motive fluid medium into an injector nozzle and piled up and stuffed in a perforated blowing chamber, the improvement which comprises introducing the individual filamentary yarns into the blowing chamber by separate yarn channels in the injector nozzle, and keeping them separate in the blowing chamber by introducing currents of fluid separating medium through separate fluid channels disposed inbetween the separate yarn channels while piling and stufiing the filamentary yarns in the blowing chamber.

2. The process of claim 1, wherein the individual filamentary yarns are kept separate by partial currents of the motive fluid medium.

3. The process of claim 1, wherein the individual filamentary yarns are kept separate by a fluid medium different from the motive fluid medium which comprises a separating medium, and the separating medium being introduced between the individual filamentary yarns.

4. The process of claim 1 wherein at least one of the motive fluid medium and the separating medium is reactive with the yarns to cause a permanent crimp of the yarns.

5. The process of claim 1, wherein the fluid medium is inert and causes a temporary dense packing of the filamentary yarns. 

1. In a process for crimping filaments and yarns in which a plurality of filamentary yarns are drawn by the current of a motive fluid medium into an injector nozzle and piled up and stuffed in a perforated blowing chamber, the improvement which comprises introducing the individual filamentary yarns into the blowing chamber by separate yarn channels in the injector nozzle, and keeping them separate in the blowing chamber by introducing currents of fluid separating medium through separate fluid channels disposed inbetween the separate yarn channels while piling and stuffing the filamentary yarns in the blowing chamber.
 2. The process of claim 1, wherein the individual filamentary yarns are kept separate by partial currents of the motive fluid medium.
 3. The process of claim 1, wherein the individual filamentary yarns are kept separate by a fluid medium different from the motive fluid medium which comprises a separating medium, and the separating medium being introduced between the individual filamentary yarns.
 4. The process of claim 1 wherein at least one of the motive fluid medium and the separating medium is reactive with the yarns to cause a permanent crimp of the yarns.
 5. The process of claim 1, wherein the fluid medium is inert and causes a temporary dense packing of the filamentary yarns. 